Fibreglass-lined ductwork is widely used in many commercial heating, ventilation, and air conditioning (HVAC) systems across Australia. The fibreglass liner offers two key benefits:
Thermal insulation: Helps maintain the temperature of conditioned air, preventing heat/cooling loss.
Sound attenuation: Reduces noise from HVAC equipment and adjacent spaces.
However, over time, factors like air turbulence, fluctuating temperatures, and humidity can degrade the fibreglass lining. This breakdown compromises the duct's primary seal, spreading insulation material throughout the ventilation system and into the indoor air or breathing zone. As the lining deteriorates, it can contribute to indoor air quality (IAQ) issues, potentially causing health problems. Exposure to fibreglass particles, depending on their size and type, can cause irritation to the skin, eyes, and respiratory tract.
ⓘ Fibreglass, when inhaled, can affect the respiratory system in various ways depending on the size of the fibres and the level of exposure. Larger fibres often get trapped in the upper respiratory tract, where the body can remove them through coughing or sneezing. However, smaller fibres can reach the lungs and remain there, potentially leading to irritation, coughing, and even bronchitis-like symptoms. Although these fibres do not typically break down within the lungs, most will eventually be expelled through the body's natural processes.
Long-term exposure to fibreglass, especially in occupational settings, has raised concerns, but studies have shown that the majority of fibreglass fibres are not biopersistent, meaning they don't remain in the lungs indefinitely. They tend to dissolve and be expelled over time. That said, in high amounts or prolonged exposure, fibreglass can aggravate conditions such as asthma and worsen respiratory symptoms
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Cleaning and Restoring Fibreglass-lined Ducts
Conventionally, damaged fibreglass-lined ductwork is either replaced entirely or re-insulated—both costly options. Fortunately, contemporary technologies now allow for the safe cleaning and restoration of these systems.
Whether or not ducts are fibreglass-lined, regular preventative maintenance and cleaning inline with AS 3666 are essential for ensuring proper airflow and maintaining safe IAQ. A regular maintenance schedule, in conjunction with a high-efficiency filtration system, UVC air sterilisation and advanced coil/duct coatings, protects HVAC components and building occupants in turn. Maintenance tasks should include inspecting for contaminants and moisture, air leakage, detecting problems, addressing any issues promptly, and in high risk settings the need for microbial and air sampling may be required.
However, in some cases, preventative measures may not be enough, and commercial air duct cleaning is necessary. When cleaning is required, it’s crucial that HVAC cleaning professionals follow guidelines set by the National Air Duct Cleaners Association (NADCA). Today's duct insulation products are designed to withstand the rigours of professional cleaning.
Fibreglass-lined Ductwork Cleaning Methods
- Contact Vacuuming
Cleaning fibreglass-lined ducts requires precision to avoid releasing glass particles into the HVAC system. Technicians use HEPA-filter vacuums to safely clean ducts by directly contacting duct surfaces with a brush to remove dirt and debris. - Air Washing
This method uses compressed air with a specialised "skipper" nozzle to blow out dirt and debris, which are then pulled out of the system by a vacuum collection unit. - Power Brushing
Pneumatically or electrically powered brushes loosen dirt and debris, which are vacuumed away. Flexible bristle brushes are used to prevent damage to the duct walls or insulation. - Repair and replace After cleaning, there is an opportunity to repair and replace insulation. This involves securing loose parts with tape, adding insulation using spray adhesive, and attaching new sections with pin spot welding.
- Coating as an added hygiene measure, HVAC technicians can apply advanced antimicrobial coatings (more details below)
- Contact Vacuuming
Antimicrobial Coatings for Ductwork and Fibreglass-lined Ductwork
After cleaning has been carried out, as an added hygiene measure, HVAC technicians can apply advanced antimicrobial coatings to the fibreglass-lined ductwork, which will prevent fraying or loosening of fibres and inhibit mould, mildew, and bacterial growth.
ⓘ As an Aeris Environmental Platinum partner, at Clean-Air, we opt for AerisGuard™ Duct Coating and Sealant. It offers exceptional properties for the performance and hygiene of ventilation systems. Preventing mould, and bacteria.
A significant feature of this product is its low VOC and low odour formulation, making it safe and practical to apply during regular working hours, even in sensitive environments. For example, it has been successfully used in fully functioning hospital wards without disrupting operations. This flexibility and safety make it an ideal solution for maintaining a healthy and efficient HVAC system.
These coatings also form a protective bond with the ductwork surface, preventing particles from entering the airstream. Antimicrobial treatments can be applied to both fibreglass-lined ducts and bare metal surfaces to provide long-lasting protection against microbial contamination.
Further reading...
Are there guidelines for limiting workplace exposure to fibreglass?
In 1999, the Occupational Safety and Health Administration (OSHA), along with the National Insulation Association and the Insulation Contractors Association of America, established voluntary exposure limits for breathable glass fibres in the workplace. This agreement, endorsed by the National Academy of Sciences, specifies the dimensions of glass fibres and limits exposure to no more than one breathable glass fibre per cubic centimetre of air during an eight-hour workday. For more details, refer to OSHA's guidelines [3] on exposure limits for synthetic mineral fibres.
References
[1] Phoenix Insulation Pros,Washington State Department of Health [2]https://www.mirasafety.com/blogs/news/is-fiberglass-dangerous [3]https://www.osha.gov/synthetic-mineral-fibers [4] https://aeris.com.au/shop/hvac-r/duct-coating-and-sealant
Clean ducting and properly insulated HVAC systems play a crucial role in maintaining safe, healthy indoor air. By reducing the buildup of dust, mould, and other contaminants, you can ensure lower particle counts and improve air quality for everyone in your building. At Clean-Air, our team of IICRC and NADCA certified remediation experts is equipped to clean, test, and protect your HVAC system—insulation included. If you're concerned about the air you're breathing or want to schedule an HVAC system inspection, contact our experts today.